Announcing virtualenv-multiver for Python Development

If you’ve worked with virtualenvs for Python before for development/testing, then you may have hit cases where you really wanted multiple versions of Python installed in your virtualenv. Which, you may actually have working, because virtualenv, in theory, supports this. In fact, you’re supposed to be able to do:

$ virtualenv -p python2.6 my-env
$ virtualenv -p python2.7 my-env

That’d be great, if it always worked. It doesn’t. When your virtualenv gets built, bin/python may end up being a link to bin/python2.7 (or what have you), or it may be the contents instead of a link. Subsequent installs may end up overwriting binaries, producing a python2.6 and python2.7that are both Python 2.7.

Oh and it gets worse. On Mac, with a standard Python install, these binaries actually end up invoking ../.Python, a symlink pointing to the system Python. This link is not versioned. So much for multiple Python versions in one virtualenv on the Mac.

A solution!

We fixed this. Now you can run a single command to get a working environment going, without messing with things or running into problems on the Mac. This is virtualenv-multiver.